1. Field of the Invention
The present invention relates to a lens-fitted photo film unit and a method of producing the same. More particularly, the present invention relates to a lens-fitted photo film unit within which a photo film port shutter is incorporated in a cassette and used for opening/closing a photo film passage port, and a method of producing the same lens-fitted photo film unit.
2. Description Related to the Prior Art
A lens-fitted photo film unit is sold by the assignee with a trade name Fujicolor Quick Snap Super 800 (manufactured by Fuji Photo Film Co., Ltd.), which has a housing incorporating a taking lens, a shutter mechanism and other structures for taking an exposure, and is pre-loaded with a cassette and unexposed photo film pre-drawn from the cassette. The housing and the component parts of the lens-fitted photo film unit are respectively formed from resin to reduce their cost, because of manufacture in great scale and sales at a low price. There are a number of suggestions of pre-loading a lens-fitted photo film unit with a photo film cassette having a plastic body.
There is a known new type of plastic cassette in which a photo film passage port has a photo film port shutter, not a light-shielding fabric widely used in the art of photo film cassette. The port shutter is rotatable between an open position where the passage port is open and a closed position where the passage port is closed. The closed position of the port shutter avoids entry of ambient light into the cassette through the passage port. The photo film contained therein is protected from exposure before taking photographs or before development. There is a suggestion in U.S. Pat. No. 5,452,036 for a lens-fitted photo film unit pre-loaded with this type of the cassette.
In the lens-fitted photo film unit pre-loaded with the cassette and the photo film, all the photo film is wound into the cassette after taking exposures thereon. The lens-fitted photo film unit is deposited to a photo laboratory or a photofinishing agent, who removes the cassette from a housing of the lens-fitted photo film unit, to develop the photo film. The cassette can be removed only when the port shutter is rotated to the closed position. In any photo laboratory, the cassette is removed in an illuminated room, not in a dark room. Unless the port shutter is closed, the photo film would be subjected to ambient light in the course of the removal.
It is possible to conceive a lens-fitted photo film unit including a rotating member, which is engaged with a distal end of the port shutter of the cassette in co-axial fashion, and externally operated to rotate the port shutter to the closed position. However this structure is likely to lower efficiency in removing the cassette from the lens-fitted photo film unit, because the removal requires a specialized tool and/or operation of externally driving the rotating member.
Operators in photo laboratories are obliged to handle lens-fitted photo film units of a type having a 135 photo film cassette in addition to the new type having the cassette with the port shutter. Prior to removal of the cassette from the new type, the rotating member is manually rotated as additional operation which is not required for the 135 type of the lens-fitted photo film unit. If an operator forgets to rotate the rotating member, the undeveloped photo film is inevitably subjected to ambient light. There is a problem of possible errors in removal of the cassette with port shutter.
To manufacture the lens-fitted photo film unit, darkroom stations are used only for loading of the photo film cassette and securing of a rear cover, as it is favorable to reduce darkroom operation. An illuminated room is used for positioning and mounting of the rotating member. However, the housing with the rotating member must be conveyed from the illuminated room into the dark room. It is likely that the housing while conveyed is shocked or vibrated to deviate the position of the rotating member. A key shaft of the rotating member must be oriented equally to a key hole of the port shutter before they can be fitted together. The rotating member must be repositioned when in the dark room, which causes a problem of low efficiency in assemblage.
In operation of the manufacture, the lens-fitted photo film unit is assembled by directing the front of the housing downwards or upwards while the parts are mounted thereon: the rotating member to be disposed on the top of the cassette containing chamber is moved in assemblage in a horizontal direction toward the housing. A problem lies in that the rotating member is likely to be deviated in the axial direction, or more seriously, dropped away from the housing. The assemblage may require a support mechanism for the rotating member, or a system for rearranging the rotating member in the darkroom, to raise complexity of the assembling system or expense for the same.